What Other Adverse Effect Does Marijuana Have on Health?

Effects on the HeartMarijuana increases heart rate by 20–100 percent shortly after smoking; this effect can last up to 3 hours. In one study, it was estimated that marijuana users have a 4.8-fold increase in the risk of heart attack in the first hour after smoking the drug.7 This may be due to the increased heart rate as well as effects of marijuana on heart rhythms, causing palpitations and arrhythmias. This risk may be greater in aging populations or those with cardiac vulnerabilities.

Effects on the LungsNumerous studies have shown marijuana smoke to contain carcinogens and to be an irritant to the lungs. In fact, marijuana smoke contains 50–70 percent more carcinogenic hydrocarbons than does tobacco smoke. Marijuana users usually inhale more deeply and hold their breath longer than tobacco smokers do, which further increase the lungs’ exposure to carcinogenic smoke. Marijuana smokers show dysregulated growth of epithelial cells in their lung tissue, which could lead to cancer;8 however, a recent case-controlled study found no positive associations between marijuana use and lung, upper respiratory, or upper digestive tract cancers.9 Thus, the link between marijuana smoking and these cancers remains unsubstantiated at this time.

Nonetheless, marijuana smokers can have many of the same respiratory problems as tobacco smokers, such as daily cough and phlegm production, more frequent acute chest illness, and a heightened risk of lung infections. A study of 450 individuals found that people who smoke marijuana frequently but do not smoke tobacco have more health problems and miss more days of work than nonsmokers.10 Many of the extra sick days among the marijuana smokers in the study were for respiratory illnesses.

Effects on Daily Life Research clearly demonstrates that marijuana has the potential to cause problems in daily life or make a person’s existing problems worse. In one study, heavy marijuana abusers reported that the drug impaired several important measures of life achievement including physical and mental health, cognitive abilities, social life, and career status.11 Several studies associate workers’ marijuana smoking with increased absences, tardiness, accidents, workers’ compensation claims, and job turnover.

What Treatment Options Exist?

Behavioral interventions, including cognitive behavioral therapy and motivational incentives (i.e., providing vouchers for goods or services to patients who remain abstinent) have shown efficacy in treating marijuana dependence. Although no medications are currently available, recent discoveries about the workings of the cannabinoid system offer promise for the development of medications to ease withdrawal, block the intoxicating effects of marijuana, and prevent relapse.

The latest treatment data indicate that in 2006 marijuana was the most common illicit drug of abuse and was responsible for about 16 percent (289,988) of all admissions to treatment facilities in the United States. Marijuana admissions were primarily male (73.8 percent), White (51.5 percent), and young (36.1 percent were in the 15–19 age range). Those in treatment for primary marijuana abuse had begun use at an early age: 56.2 percent had abused it by age 14 and 92.5 percent had abused it by age 18.**

How Widespread is Marijuana Abuse?

National Survey on Drug Use and Health (NSDUH)***According to the National Survey on Drug Use and Health, in 2007, 14.4 million Americans aged 12 or older used marijuana at least once in the month prior to being surveyed, which is similar to the 2006 rate. About 6,000 people a day in 2007 used marijuana for the first time—2.1 million Americans. Of these, 62.2 percent were under age 18.

Monitoring the Future Survey****The Monitoring the Future survey indicates that marijuana use among 8th-, 10th-, and 12th-graders—which has shown a consistent decline since the mid-1990s—appears to have leveled off, with 10.9 percent of 8th-graders, 23.9 percent of 10th-graders, and 32.4 percent of 12th-graders reporting past-year use. Heightening the concern over this stabilization in use is the finding that, compared to last year, the proportion of 8th-graders who perceived smoking marijuana as harmful and the proportion who disapprove of the drug’s use have decreased.